Heart failure (HF) after myocardial infarction (MI) is a significant cause of morbidity and mortality. Identifying the events that limit adverse remodeling of the left ventricle (LV) post-MI will provide therapeutic targets to prevent, slow, or reverse progression to HF. MI initiates the ?get-in? signal for immune cells including neutrophils, which if unchecked causes uncontrolled pro-inflammatory activity that in turn leads to HF. Our post-MI studies suggest that spleen coordinates the resolution of inflammation through a cardiosplenic pathway. These findings reveal an urgent clinical need to establish the mechanisms by which the spleen mediates this resolution. It was previously believed that resolution of inflammation is an inert process, but emerging data confirms that this is an active process managed by specialized pro-resolving molecules (SPMs) derived from omega-3 and omega-6 fatty acids. Our R00 study in an HF setting confirms that the spleen produces various SPMs, including lipoxins, resolvins, and maresins post-MI, and exogenous treatment with resolvin D1 (RvD1) clears inflammation in a cardiosplenic manner. We discovered that exogenous RvD1 clears neutrophils and resolves inflammation by activating neutrophil-expressed formyl peptide receptor 2 (FPR2) in the left ventricle and spleen post-MI. This proof-of-concept study using RvD1 in mice provides the foundation for investigation of the resolvins-mediated mechanism of action in chronic HF. These data implicate activation of neutrophil receptors in promoting the ?get-out? signal for effective resolution of inflammation post-MI. To achieve our overall goal of activating immune cells in the healing phase after MI, we propose to establish: 1) the role of RvD1 in resolution of inflammation in chronic HF; 2) whether activation of this ?get-out? signal is enough to resolve post-MI inflammation in HF using FPR2 knockout mice to abolish RvD1 action and resultant HF; and 3) the novel mechanism of action of RvD1 on neutrophil-expressed CD10 in the cardiosplenic axis, as suggested by our innovative in silico computational modeling. Our initial studies in mice have confirmed the role of RvD1 in acute HF. Now, we propose a mechanistic study to extend in silico, ex vivo, and acute HF (day 5) outcomes to chronic HF (day 28), which is key for translation and to indicate survival benefit to HF patients. Non-immunosuppressive pro-resolving therapy is an unmet medical need and has the potential to be the first ever effective therapy to control chronic inflammation and delay HF in a cardiosplenic manner. These studies will identify immune cell-specific novel targets for lipid mediators in a ligand-receptor-specific pathway, rather than antibody or cytokine-specific inhibition, which will likely enhance therapeutic applications in patients with HF within the next 5-6 years.